Microsoft Word Hole Could Allow DoS Attacks

Kimberly Hill, www.enterprise-security-today.com

Computer security firm Secunia has reported what it terms a "highly critical" vulnerability in the popular Microsoft (Nasdaq: MSFT - news) Word desktop computer application. The firm has confirmed the existence of the hole in versions of Word as recent as Word 2000
The problem appears to affect only documents that are opened from or downloaded from Web sites, Secunia CTO Thomas Kristensen told NewsFactor. However, the installation of the Microsoft Office suite has many options, and vulnerabilities related to local documents may exist, he added.
The fix, says the company, is to open only documents from trusted sources.
Deliberate Crash
An input validation error related to the parsing of document files and errors creates the vulnerability by establishing a stack-based buffer overflow, says Secunia. When a user opens a document designed to take advantage of the flaw, the process will crash. At the same time, other code could be executed.
Then, through that hole, hackers may be able to launch a denial-of-service (DoS) attack using the compromised machine. However, this part of the reported security flaw has not been proven, says Secunia.
Set Security High
Users who run Internet Explorer can avoid the problem by opening Word documents on Web sites within their browser software rather than using Word.
To ensure the safety of this process, users should make sure that the security level for the Internet security zone is set to high or that the file-download option has been disabled.
A group of researchers called "HexView" originally brought up the possibility of an issue with Word, Kristensen said. When a security problem has not been verified by the software vendor, he said, his firm is particularly careful to research and verify the details.
So far, Secunia has determined that the buffer-overflow problem does exist. It is working to gather information that, if deemed useful, will be provided to Microsoft.